CVE-2026-63865
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedIn the Linux kernel, the following vulnerability has been resolved: bpf: Drop task_to_inode and inet_conn_established from lsm sleepable hooks bpf_lsm_task_to_inode() is called under rcu_read_lock() and bpf_lsm_inet_conn_established() is called from softirq context, so neither hook can be used by sleepable LSM programs.
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceThe Linux kernel's BPF LSM (Linux Security Module) hooks for task_to_inode and inet_conn_established are incorrectly exposed to sleepable programs. bpf_lsm_task_to_inode() is called under rcu_read_lock() and bpf_lsm_inet_conn_established() is called from softirq context - neither permits sleepable operations. This mismatch could cause issues if sleepable LSM programs attempt to use these hooks.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Local
- Complexity
- Low
- Privileges
- Low
- User interaction
- None
- Scope
- Changed
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Verify BPF LSM is activeCheck if BPF LSM is loaded: 'lsmod | grep bpf' and look for 'bpf_lsm' or check /sys/kernel/security/bpf if it exists. Also check kernel config for CONFIG_BPF_LSM=y and CONFIG_BPF_LSM_MAKE_SLEEPABLE=yAffected if BPF LSM is not enabled or not configured with sleepable programs, the issue does not apply
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Identify sleepable BPF programsList installed BPF programs: 'bpftool prog list' and look for type 'lsm' with 'sleepable' flag set to 1. Check if any use the 'task_to_inode' or 'inet_conn_established' hooksAffected if No sleepable BPF LSM programs are loaded, the functional issue cannot manifest
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Inspect sleepable hooks configurationExamine the kernel source file containing the sleepable hooks list (typically in security/bpf/ directory) and verify whether 'task_to_inode' and 'inet_conn_established' appear in the sleepable hooks arrayAffected if These hooks are present in the sleepable hooks list, sleepable programs attempting to use them will fail
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Check hook invocation contextReview kernel source or use tracing to confirm bpf_lsm_task_to_inode() runs under rcu_read_lock() and bpf_lsm_inet_conn_established() runs in softirq context rather than process contextAffected if Hooks are callable from sleepable context (process context allowing blocking), the classification mismatch does not exist
A system is affected if BPF LSM is enabled with sleepable programs AND those programs attempt to use the task_to_inode or inet_conn_established hooks, since these hooks run in non-sleepable context despite being listed as sleepable.
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
From vendor dataRemove these hooks from the sleepable LSM hooks list in the kernel via a kernel update/patch. Systems should update to the patched kernel version.
- Consultation4.0 h
- Implementation4.0 h
- Testing8.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,504.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-63865 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2026-63865 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Version or environment caveats, and links to real fixes
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